Methylenediphosphine products and process for the preparation thereof



3,253,033 METHYLENEDIPHOSPHINE PRODUCTS AND PROCESS FOR THE PREPARATION THEREOF Ludwig Maier, Zurich, Switzerland, assignor to Monsanto Company, a corporation of Delaware No Drawing. Filed Aug. 16, 1962, Ser. No. 217,292 Claims priority, application swiltzerland, Aug. 25, 1961, 13/6 15 Claims. (Cl. 260570.5)

It has been found that by reacting substituted or unsubstituted aminomethylphosphines with hydrogen phosphide, monoor diorganophosphines, there are formed methylenediphosphines which contain at least once the grouping P-CH P. The expression unsubstituted or substituted aminomethylphosphines signifies that on the phosphorus atom may be only aminomethyl radicals or in addition to 1 or 2 aminomethyl radicals, 2 or 1 hydrocarbon radicals.

The preparation of the aminomethylphosphines serving as starting materials is well known. They can be obtained for example from substituted or unsubstituted hydroxymethylphosphonium salts and primary or secondary amines (Bnit. P. 842,593 Albright and Wilson Mfg. Ltd., Oldburry), or, hydrogen phosph'ide, primary or secondary phosphines and either formaldehyde and primary or secondary amines, or 'methylolamines, or primary or secondary methylenediamines (German patent application 1,096,905, Albright and Wilson Mfg. Ltd, Oldburry). These reactions are represented by equation as follows:

(1) Hydroxymethylphosphonium salts primary or secondary amines, or

(2) PH or PH R or PHR -l-primary or secondary amines-l-formaldehyde, or

(3) PH or PH R or. PHR -i-methylolamines.

In all of the above reactions primary or secondary diamines can be used instead of monoamines. The oxygen or sulfur analogs reactants are prepared by oxidation or sulfurization techniques discussed hereinbelow.

One reactant for carrying out the instant invention, corresponds to the general formula R is an alkyl, aralkyl, cycloalkyl, aryl or heterocyclic radical which can have as a substituent another phosphino group. When two Rs are present, they can form together with the phosphorus atom a heterocyolic ring. One R can also be a similar phosphino group resulting in a di-phospine. R and R" are alkyl, aralkyl, cycloalkyl, aryl or heterocyclic radicals which can be unsaturated and/ or substituted, or R" can also be a hydrogen atom, or R and R" can form together with nitrogen 21 heterocyclic ring like pyrrole, piperidine, morpholine; a is 0, 1 or 2. The NR'R part of at least one aminomethyl substitu'ent is derived from a primary or secondary amine easily volatile. Bearing in mind limitations set forth in the previous sentence and elsewhere herein, R, R and R" will each normally contain not more than 18 carbon atoms and usually not more than 8 carbon atoms.

R, R and R" may be identical or different and also be unsaturated and/or substituted, to the extent that substituents present do not disturb the reaction.

For the present process aminomethylphosphines are also United States Patent "ice 3,253,033 Patented May 24, 1966 suitable which correspond to, for example, one of the following formulae:

RPCHBNRINC HEPR PCH1NRNCH1 or the oxygen or sulfur analogs can be used. It is assumed that the molecule part R"N-R'NR" is a radical of a volatile d-iamine such as diaminoeth ane, di(methylamino)ethane. When in the above formulae R is replaced by a group R"RNCH being capable of undergoing the reaction, the molecule ipart RNRNR" may be, of course, also derived from a difliculty or non-volatile diamine, such as piperazine, phenylenediamine and melamine.

The simplest aminophosphorus derivatives suitable to put into practice the process are, e.g., P(CH NHCH 2 3)2la, 3 2 3)2 CH P [CH N(CH 1 (CH PCH NHCH The second reactant is of the general formula R PH wherein R and 0 again possess the significance mentioned above are use-d as a second reactant in the process of invention. The simplest representatives are, e.g., PH CH PH (CH PH. However, also included are compounds, such as H PPH RHP-PHR H PR'PH RHP- "'-PHR(R"=hydrocarbon radical) since these can be reacted in a similar way.

According to the reactants and to their stoichiometric ratio, there can be formed methylenediphosphines which show one, two, three or more successive PCH P bonds, or the oxygen or sulfur analogs thereof. Conse quently such compounds are methylenediphosphines, dimethylenet-riphosphines, branched trimethylenetetraphosph'ines, cyclic methylenediphosphines (4- and S-memibered rings) or polymeric methylenediphosphines, or oxygen or sulfur analogs, all of which are based on one of the following illustrated backbone:

wherein X is an oxygen or sulfur atom and b is 0 or 1. A methylenediphosphine is obtained by reacting a mono- (aminomethyDphosphine with a secondary phosphine according to the equation: (I) R PCH NR'R"|-R PH R PCH PR +R'RNH It is obvious to one skilled in the art that the organic radicals R in the amino ethylphosphine derivative and in the phosphine may be like or unlike, and as a result there are formed symmetric or unsymmetric methylenediphosphines. It is also clear that, if two radicals are attached to the one phosphorus atom, these may be different from one another.

A dimet-hylenetriphosphine is obtained by reacting either a bis(aminomethy1)phosphine derivative With twice an equimolar amount of a secondary phosphine, or, a primary phosphine with twice an equimolar amount of a mono(aminomethyl)phosphine derivative. This reaction occurs according to one of the following equations:

RP(C IIZNRR)2 21121 11 RzPCIIzP-CHzPRz 2RRNH l1 ZRzPClIzNRR R1 1Iz (III) Branched trimethylenetetraphosphines are obtained by reaction of either a tris(aminomethyl)phosphine with three times the equimolar quantity of a secondary phosphine, or, hydrogen phosphide with three times the equi- 2 molar quantity of a mono(aminomethyl)phosphine derivative:

Cyclic or polymeric methylenediphosphines are formed by reaction of equimolar quantities of a bis(aminomethyl) phosphine derivative and of a primary phosphine:

(aminomethyl)phosphine derivative and hydrogen phos- 50 phide, or, -a tris(aminomethyl)phosphine and a secondary phosphine in suitable proportions:

(VII) According to the stereochemical facts which are present, a bicyclic tetramethylenetetraphosphine can be formed. In this case n then is 1 and the phosphorus 60 atoms each are linked through methylene groups via indicated valencies not yet occupied.

Finally, polymers are obtained which contain a great number of such S-membered rings in sequence, when equimolar quantities of a tris(aminomethyl)phosphine and 65 hydrogen phosphide are brought to reaction:

2 n P(CI -IzNRR)a 2 11 PH;

C Hz- P-C Hr-P- CH2 CH2 CHzPCHz-P n The expert will easily recognize that the degree of cross-linking can be varied in the reaction (VI) by adding a definite amount of a trifunctional phosphine which Will act as a cross-linking agent, or, in the reactions (VII- IX) by varying the molar proportions of the reaction partners.

It has further been found that the reaction of invention can also be carried out so that one or more aminomethyl groups will be preserved in the end products. The preparation of such aminomethyl-containing methylenediphosphines, dimethylenetriphosphines, trimethylenetetraphosphines, cyclic and polymeric methylenediphosphines is -a further object of this invention. In this case, bisand tris(aminomethyl)phosphine derivatives are needed as starting materials. These are reacted with hydrogen phosphide, primary or secondary phosphines on principle in a similar manner. Hereby, the ratio of the hydrogen atoms attached to the phosphorus atom and the aminomethyl substituents present in the reaction mixture has always to be smaller than 1:1, and, as a rule, to be 1:2, 2:3 or 1:3. The reaction proceeds, for example, according to the scheme:

From equimolar quanties of a tris(aminomethyl)phosphine and a primary phosphine are obtained cyclic methylenediphosphines which contain aminomethyl as substituents:

Amine radicals are always replaced by phosphine radicals in the reaction of invention. The radical NR'R" therefore is such of an easily volatile amine, e.g. methylamine, dimethylamine, ethylamine, diethylamine, if such radicals are all to be replaced. In the second class of end products which still contain one or more aminomethyl groups, the radical NRR" can be derived from any amine, even being difiicultly volatile or non-volatile, provided that a radical NR'R of such an amine which is easily volatile at the reaction temperature is also present in the starting material or reactant. Such a radical is necessary for the reaction. The reaction between aminomethylphosphine derivatives and phosphines is achieved by heating the reactants in the calculated proportions. The reaction tem perature depends on the reactivity of the reactants. It lies generally in the range of about l00 250 C. One can work with or without a solvent. Hydrogen phosphide is conveniently reacted in an autoclave. The reaction is preferably carried out in an inert atmosphere, like nitrogen, since the phosphines are very easily oxidized. The course of the reaction can be followed up by the determination of the amount of amine which is split off.

Methylenediphosphines have not been known, except the simplest compound R PCH PR Methylenediphosphines containing one or several aminomethyl substituents are novel too. The end products of invention can be used as polymerization catalyst, flame-proofing agent and pesticide. Moreover, they are strong complexing agents and can be used for, e.g., the extraction of metal salts from aqueous solution. The polymeric methylenediphosphines are, according to the organic substituents present, liquid, waxor resin-like products. They can be used as adhesive, or be converted into shaped goods, so far as their nature permits. The methylenediphosphines further are valuable intermediates. By direct oxidation with elemental oxygen e.g., by injecting oxygen or air using a gas distributor with cooling and stirring, or, by treating the aqueous suspension with hydrogen peroxide or other suitable oxidizing agents, the methylenediphosphines are converted into the corresponding oxides, which are complexing agents too. The analogous sulfides are obtained in a manner known per se by the action of elemental sulfur, suitably in a solvent like CS Example 1 14.5 g. of tris- (diethylaminomethyl)phosphine and 9.3 g. of diphnylphosphine (molar ratio 1:1) are heated at 140 C. Thereby 1.7 g. of diethylamine is distilling ofi (=45% of the theory). The residue is fractionally distilled and the compound [C H NCH PCH P(C H is obtained in form of a colorless liquid.

Yield 9 g. (=40%); B.P. 142-43 C./0.01 mm.

Analysis.C H N 'P Calc.: C, 68.65; H, 9.01; N, 6.96.

Found: C, 69.64; H, 9.02; N, 6.84.

On oxidation with KMnO; in acetone, the oxide z shNcHzlzfcHzfi( in form of a colorless liquid.

Yield 5 g. (=35% of the theory); B.P. 210 C./0.05

Analysis.C H N-P Calc.: C, 73.26; H, 7.43; N, 3.56;

P, 15.75. Found: C, 72.97; H, 7.20; N, 3.37; P, 16.34.

The oxide,

melts at 183-4.5 C.

An'alysis.C H NP O Calc.: C, 67.75; H, 6.87; P,

14.56. Found: C, 68.01; H, 6.15; P, 14.45. 1

Example 3 Equimolar quantities of (C H PCH N(C H and HP(C H are heated at 150-80" C. in a nitrogen atmosphere for 2 hours. Thereby diethylamine is distilling off. The reaction product is (C H PCH P(C H Yield: quantitative; M.P. 122 C.

Analysis. C H P (384.4): Calc.: 78.11; H, 5.77.

Found: C, 78.66; H, 5.67.

Example 4 20 g. (0.07 mole) of C. H P[CH N(C H (B.P. 165-90 C./0.05 mm., n 1.5308) and 26.6 g. (0.14 mole) of HP(C H are heated at 160 C. in a nitrogen atmosphere for 8 hours. Thereby the theoretical amount of diethylamine is distilling off. The viscous liquid is cooled at room temperature and crystallized after a few days. It consists of 6 Yield: quantitative; M.P. 107110 C.; B.P. -140 C./10 mm.

Analysis.C H P (506.5): Calc.: C, 75.88; H, 5.77;

P, 18.34. Found: C, 76.2; H, 5.33; P, 17.40.

Example 5 20 g. mole) Of C6H5P[CH2N(C2H5)2]2 and 7.9 g. (0.07 mole) of H PC H are heated at C. in a nitrogen atmosphere for 4 hours. Thereby the theoretical amount (10.2 g.) of diethylamine is distilling off. The viscous liquid is cooled at room temperature and crystallizes on addition of alcohol. It contains Yield: quantative.

One part of the product melts at 1257 C. and has a molecular weight of 500 (determined by cryoscopic method in benzene). The symbol p in this product therefore is 4 and it is an eight-membered ring of the formula AnaIlysis.C H P (488.4): Calc.: C, 68.85; H, 5.78;

P, 25.4. Found: C, 67.33; H, 5.57; P, 27.2.

Also, another product has also been isolated which melts at 134-6 C. It is a higher polymeric product.

AnalySiS.(CqHqP) Calc.: C, 68.85; H, 5.78. Found:

On oxidation of the cyclic methylenediphosphine which is composed of eight-membered rings, by employing a technic usual in the oxidation of phosphines, the corresponding tetra-oxide is obtained. This compound is an excellent complexing-agent for metals and metal salts.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for preparing a compound having at least one PCH P grouping comprising heating in an inert atmosphere a first compound of the formula wherein each R is selected from the class consisting of the phenyl group, and alkyl and alkaryl hydrocarbon having not more than 8 carbon atoms; R is selected from the class consisting of the phenyl group, and alkyl and alkaryl hydrocarbon having not more than 8 carbon atoms; R" is selected from the class consisting of R and a hydrogen atom, a is an integer from 0 to 2, and a second compound of the formula wherein R and a are as defined hereinabove, at a temperature in the range of about 100-250" C. and for a time sufilcient to split off and to volatilize in the form of a secondary amine the portion R'RN of at least one aminomethyl substituent derived from an easily volatile amine.

2. A process of claim 1 wherein R for the second compound is the phenyl group, R and R" are each alkyl having not more than 8 carbon atoms, a of the first compound is 0, and a of the second compound is 2.

3. A process of claim 1 wherein each R is the phenyl group, R and R are each alkyl having not more than 8 carbon atoms, the a for the first compound is one, and the a for the second compound is two.

4. A process of claim 1 wherein each R is the phenyl group, R and R are each alkyl having not more than 8 carbon atoms, and a is two for both compounds.

5. A process of claim 1 wherein each R is the phenyl group, R and R are each alkyl having not more than 8 carbon atoms, a for the first compound is one, and a for the second compound is two.

6. A process of claim 1 wherein each R is the phenyl group, R and R" are each alkyl having not more than 8 carbon atoms, and a for both compounds is one.

7. A compound of the formula wherein at least one of the valences of a phosphorus atom is satisfied with an RRNCH R is selected from the class consisting of the phenyl group, and alkyl and alkaryl hydrocarbon having not more than 8 carbon atoms, and R" is selected from the class consisting of R and a hydrogen atom group, and the other valences of the phosphorus atom are satisfied by R and each R is selected from the class consisting of the phenyl group, and alkyl and alkaryl hydrocarbon having not more than 8 carbon atoms, each X is selected from the class consisting of oxygen and sulfur atoms, and b is an integer from to l.

8. A compound of the formula wherein each R is the phenyl group, and R and R" are each alkyl having not more than 8 carbon atoms.

9. A compound of the formula wherein each R is the phenyl group, and R and R" are each alkyl having not more than 8 carbon atoms.

10. A compound of the formula wherein each R is the phenyl group, and R and R are each alkyl having not more than 8 carbon atoms.

11. A compound of the formula R'RNCH P (R) CH PR wherein R is the phenyl group, and R and R" are each alkyl having not more than 8 carbon atoms.

12. A compound of the formula wherein each R is the phenyl group, and R and R are each alkyl having not more than 8 carbon atoms.

13. A compound of the formula wherein each R is the phenyl group.

15. A polymer having the formula wherein R is the phenyl group, and p representing the degree of the polymerization is an integer greater than 4.

References Cited by the Examiner UNITED STATES PATENTS 2,642,461 6/1953 Morris et al. 260-606.5 3,035,053 5/1962 Coates et al. 26O-2 3,044,984 7/1962 Bloomfield 260-2.

CHARLES B. PARKER, PrimaryvExaminer.

WILLIAM H. SHORT, Examiner. 

1. A PROCESS FOR PREPARING A COMPOUND HAVING AT LEAST ONE PCH2P GROUPING COMPRISING HEATING IN AN INERT ATMOSPHERE A FIRST COMPOUND OF THE FORMULA
 7. A COMPOUND OF THE FORMULA
 13. A COMPOUND OF THE FORMULA
 15. A POLYMER HAVING THE FORMULA 